Morning coffee reduces health risk, but drinking it all day does not

Morning coffee reduces health risk, but drinking it all day does not

Drinking coffee at the right time of day could be the key to a longer, healthier life - discover how your morning coffee can protect your heart and increase longevity!

In a recently published study in theEuropean Heart JournalResearchers in the United States examined the associations between coffee drinking (specifically the timing of coffee consumption) and mortality (general or cause-specific). Their analyzes of more than 42,000 U.S. adults from the National Health and Nutrition Examination Survey (NHANES) and the Women's and Men's Lifestyle Validation Study (WLVS and MLVS) revealed two distinct clusters - those who consumed coffee in the morning hours (morning type) and those who drank coffee throughout the day (all-day type).

The study results showed that the morning type cluster had significantly lower cardiovascular disease (CVD) and all-cause mortality than non-coffee drinkers or the all-day cluster participants, suggesting that moderate coffee consumption during the morning hours could help reduce mortality risk and extend life expectancy of the US population. However, the study emphasizes that this is an observational finding and causality cannot be confirmed.

background

Coffee brewed from roasted coffee beans is one of the most popular drinks worldwide. Several prospective studies have examined the health effects of coffee consumption. The results suggest that coffee in moderation may reduce the risk of type 2 diabetes (T2D), cardiovascular diseases (CVDs), and all-cause mortality. These benefits prompted the United States (US) Dietary Guidelines (2015–2020) to include moderate coffee consumption in their recommendations for healthy dietary products.

Circadian Disruption and Health: Consuming coffee later in the day can disrupt circadian rhythms and reduce melatonin levels, which are crucial for cardiovascular health, and reduce oxidative stress.

Unfortunately, caffeine (a stimulant found in coffee beans and, to a lesser extent, tea) has been reported to be addictive, prompting studies to examine the effects of excessive coffee consumption (>3 cups/day). However, coffee tolerance and coffee consumption vary due to a variety of factors, including genetics, behavior (e.g., smoking), and additives (e.g., sweeteners), confounding the results of these studies, most of which involve limited sample sizes.

Recent research has increasingly highlighted the importance of circadian rhythms in regulating human metabolism and health outcomes. Studies suggest that the timing of food intake can significantly influence its impact on health. Although coffee is often used to stay awake and prevent sleepiness due to its stimulating effects, the effects of coffee consumption at different times of the day remain largely unexplored.

About the study

The present study uses cluster analysis to identify patterns in coffee consumption in a large US population (n = 42,188) and then examine the associations between these patterns and mortality risk. Study participants were derived from the National Health and Nutrition Examination Survey (NHANES; n = 40,725), with an additional sample cohort - the Women's and Men's Lifestyle Validation Study (WLVS and MLVS; n = 1,463) - used for external validation. Participants with cardiovascular disease, pregnant women, or participants who had cancer at baseline were excluded from the analyses.

Study data were collected using 24-hour dietary recall questionnaires that included timing, amounts, and types of beverages and foods consumed in the previous midnight-to-midnight interval. In addition, in-person physical examinations were performed at baseline and during the 9.8-year follow-up period.

Statistical analyzes included generalized linear models (for covariance estimates) and chi-square models (χ2) for comparisons between variables of interest. Cluster analyzes (hybrid approach) were used to identify coffee consumption patterns. To increase the reliability of their results, the researchers also took into account numerous confounding variables such as smoking status, sleep patterns, diet quality and physical activity. Hazard ratios (HRs; Cox proportional hazards models) were then calculated to assess the associations between identified clusters and their respective all-cause and cause-specific mortality rates.

Study results

The role of decaffeinated coffee: The study included analyzes of both caffeinated and decaffeinated coffee and found similar health benefits for morning consumption, suggesting possible anti-inflammatory effects beyond caffeine.

Clustering analyzes identified two distinct patterns for timing of coffee consumption: morning (36% of participants; 4 to 11:59 a.m.) and throughout the day (16%; morning, afternoon, and evening). Surprisingly, the morning coffee drinkers consumed larger amounts of tea and caffeinated soda than their all-day drinkers (who consumed mostly coffee throughout the day).

Cox proportional hazards models revealed that morning coffee consumption reduced all-cause mortality (HR = 0.84) and CVD-specific mortality (HR = 0.69) compared to non-coffee consumers. In contrast, all-day coffee consumption was statistically indistinguishable from coffee abstinence. Importantly, coffee drinkers who drank coffee throughout the day showed neither harm nor benefit in terms of mortality risk. These results remained consistent even after adjusting for confounding variables (gender, age, sleep patterns, smoking status, etc.).

Notably, a positive correlation was observed between the amount of daily coffee consumption and mortality rate outcomes in morning participants - higher coffee consumption (>3 cups/day) improved mortality rate outcomes compared to lower coffee consumption (1 cup/day) - with hazard ratios improving from 0.85 for the latter cohort to 0.79 for the former. Again, no improvement in the amount of coffee consumed was found in mortality outcomes for all-day coffee consumers.

Conclusions

The present study is the first to examine the effects of different timing of coffee consumption on all-cause and cause-specific (CVD) mortality in a large US population. The study results identified two main types of coffee drinkers – 1. the morning type and 2. the all-day type. The results suggest that the timing of coffee consumption may play a crucial role in its health effects, possibly due to its interaction with circadian rhythms and anti-inflammatory mechanisms. The study highlights that limiting coffee consumption to the morning hours (4 a.m. to 11:59 a.m.) significantly reduces mortality rates for both all-cause and CVD-specific mortality. In contrast, coffee consumers who drink coffee throughout the day showed no such health benefits. These results highlight the need for further research to explore the causative factors and confirm the results in different populations.

“Our results highlight the importance of considering the timing of drinking in the relationship between the amount of coffee consumed and health outcomes.”

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